Pressure steam setting process

ABSTRACT

THE STEAM SETTING OF TEXTILE MATERIALS AND TEXTILE GOODS BY FIRST CONTACTING THE SAME WITH AN AQUEOUS, OR SUBSTANTIALLY AQUEOUS LIQUID BATH AND THEN PASSING THE TEXTILE MATERIALS OR GOODS INTO A POOL OF MOLTEN METAL MAINTAINED AT A SUFFICIENTLY ELEVATED TEMPERATURE THAT THE AQUEOUS PORTION OF THE FIRST LIQUID BATH IS CONVERTED TO VAPOR BEFORE THE MATERIALS OR GOODS LEAVE THE POOL OF MOLTEN METAL, THE DEPTH OF IMMERSION OF THE TEXTILE IN THE MOLTEN METAL POOL DETERMINING THE PRESSURE THEREBY DEVELOPED, WHEREBY THE TEXTILE IS EXPANDITIOUSLY SET WITHOUT RECOURSE TO THE USE OF EXTERNAL SUPERATMOSPHERIC PRESSURE.

United States Patent US. Cl. 8-1491 6 Claims ABSTRACT OF THE DISCLOSURE The steam setting of textile materials and textile goods by first contacting the same with an aqueous, or substantially aqueous, liquid bath and then passing the textile materials or goods into a pool of molten metal maintained at a sufiiciently elevated temperature that the aqueous portion of the first liquid bath is converted to vapor before the materials or goods leave the pool of molten metal, the depth of immersion of the textile in the molten metal pool determining the pressure thereby developed, whereby the textile is expeditiously set without recourse to the use of external superatmospheric pressures.

This invention relates to the setting of textured or crimped yarns, knit hosiery and other textile products. More particularly, it relates to procedures whereby such processes may be carried out with the use of a pool of molten metal expeditiously and in an automatic, continuous manner.

The use of molten metal in the treatment of textiles is known. In one process described in US. Pat. 2,693,995 and 3,077,370 and others, textile material to be dyed is passed through a bath of an aqueous dye liquor containing vat and sulfur dyes and then into a bath of molten metal maintained at a temperature below which any substantial ebullition of the dye liquor occurs.

The process of the present invention presents a number of advantages and distinctions from such prior art processes in which a molten metal bath has been utilized for the treatment of textile materials. As taught in the prior art, by the use of a molten metal alloy bath as the heating medium a number of advantages are obtained, including rapid and uniform heating of the goods being treated. Furthermore, the molten metal tends to keep the treating liquid and steam in close physical contact with the goods, since the treating liquor and steam are incompatible with the molten metal.

In conventional texturing processes, monofilaments or threads of fibers are often twisted around each other, knitted or caused in some other manner to take an undulating form. While held in this position or configuration, the fibers are permanently heat set with dry heat or steam. Upon unraveling, untwisting or de-knitting, the monofilaments or single threads are permanently imparted with an undulating form. Such processes, setting is generally accomplished with dry heat with consequent dehydration of the yarn and other adverse physical effects. In one aspect of the present invention crimped, twisted or textured yarns may be permanently steam set without resorting to external superatmospheric pressure. Setting in a saturated, high pressure steam atmosphere is considered to be more desirable, but has been considered to be impractical because there is no continuous way to carry the filaments into a zone of high pressure steam and back out again.

In the present invention the yarn, filaments of knit construction in the unset or relaxed state is moistened with water, water containing wetting agents, or water containing treating agents such as aqueous dye liquor, and the moistened textile material is conveyed into a molten metal bath maintained at a temperature above the boiling point of water. If the moist textile product is carried only a short distance below the molten metal surface, the steam which develops will be at close "to atmospheric pressure and at a temperature of about 212 F. However, as the textile product is carried deeper into the molten metal bath the pressure and temperature reached will be determined by the pressure exerted by the height of the column of dense metal above. Therefore, the desired steam pressure or temperature may be obtained by providing molten metal at or above the desired steam temperature, causing the goods to be immersed to such an extent that the pressure exerted by the overlying molten metal is equal to the steam pressure desired. For practical purposes, however, it is desirable to maintain the molten metal bath at least 10 F. above the steam temperature desired in order to improve the rate of heat transfer into the liquid.

The present invention therefore departs from known prior art processes particularly with reference to the temperature of the liquor, the temperature of the molten metal bath, the ability to control steam temperature and pressure and is directed to the setting of textile goods.

The following examples illustrate the invention in its simplest form and are not intended to limit the invention. Two ends of 3-filament nylon 6 yarn of 18 denier was given a false twist of turns/inch using a Turbo Duotwist (Manufactured by Turbo Machine Company, Lansdale, Pa.) or other suitable texturing machine. The twisted yarn was wet with water by drawing it through a wet felt wick. The wet, twisted ends were then carried into a bath of low melting bismuth alloy sold as Cerrosafe which melts at to F. The bath was maintained at a temperature of 253 F. The bismuth alloy has a density of 9.4 (0.339 pound/cubic inch). Therefore, by carrying the twisted ends to a depth of 35 inches into the molten metal bath, a steam pressure of 12 p.s.i.g. was developed and, according to standard steam tables, the steam has a temperature of 243 F. In the actual test, the yarn so treated was untwisted and found to be perfectly set without having been dehydrated as in dry setting processes.

Example 2, two ends of false twisted l3-filament 40 denier nylon 66 yarn were wet with a solution consisting of 99.9% water and 0.1% of an alkyl aryl polyether alcohol containing 9 to 10 ethylene oxide groups and sold by Rohm & Haas Co. under the tradename of Triton X-lOO. The addition of this wetting agent to the water gave better wetting of the nylon 66 yarn. The wet yarn was drawn into a molten metal bath in which the molten metal was an alloy sold under the tradename of Cerrobase (Cerro Copper & Brass Co.) which has a melting point of 255 F. The bath was maintained at 255 F. The specific gravity of the molten metal is 10.3, thus the weight per cubic inch is 0.372 pounds. The twisted yarn was carried down to a depth of 48 inches which, according to standard steam tables, produced a steam temperature of 255 F. and a pressure of 18 p.s.i.g. After the yarn was removed from the bath it was untwisted and the crimped yarns were found to be more satisfactory than dyeings obtained with dehydrated yarns set with dry heat.

When heat setting polyester yarns with dry heat it is well known that contact with oxygen causes a severe and permanent yellowing of the fiber. The use of the present invention accomplishes setting in a steam atmosphere free of oxygen and eliminates such yellowing.

In order to prevent oxidation of the molten metal bath it has been found to be advantageous to blanket the top surface with an inert gas such as nitrogen, argon, helium or other noble gas.

It will be noted that all moisture on the textile product, Whether deliberately added or as a result of a previous dyeing process, is converted to steam and a dry product emerges from the molten metal bath.

The present invention can be applied to fabricated knit items, by placing them on shaped boarding forms, wetting them with aqueous liquids, and then immersing the boarding forms and goods thereon in a suitable molten metal bath and steam set them to shape.

By the addition of thermosetting water soluble or dispersible resin finishes or treatments to the moistening liquid, finishes may be applied to the goods while they are being set. During the molten metal treatment of the textile the water is converted to steam leaving a uniform resin coating behind which cures during its passage through the heated bath. Examples of suitable resins include watersoluble urea and melamine monomers or other low molecular weight resins.

Having now described the invention in accordance with the patent statutes, it is not intended that it be limited except as may be required by the appended claims.

What is claimed is:

1.. A process for steam setting of textile materials and textile goods which comprises:

moistening the textile by contact with an aqueous liquid; and then passing the moistened material into a molten metal bath,

the depth to which the moistened material is carried being such that the pressure of the molten metal on the moistened material is such that the temperature of the steam generated from the moisture on the ma- 4 terial is sufliciently elevated to cause setting of the textile material.

2. The process of claim 1 wherein the aqueous liquid contains an additive for imparting a finish to the textile.

3. The process of claim 1 wherein the aqueous liquid contains a wetting agent.

4. The process of claim 1 wherein the molten metal is maintained at a temperature at least 10 F. above the steam temperature desired for setting.

5. The process of claim 1 wherein the molten metal is a low melting alloy based on bismuth, cadium, lead or other low melting metal.

6. The process of claim 1 including:

providing an inert atmosphere above the molten metal whereby oxidation of the molten metal is prevented.

References Cited UNITED STATES PATENTS 2,693,995 11/ 1954 Hannay et al. 68-9 WILLIAM I. PRICE, Primary Examiner U.S. Cl. X.R.

8-1493, Digest 19 

